Nebraska Sen. Ben Nelson (D) on Monday announced he would oppose Craig Becker’s nomination to the National Labor Relations Board (NLRB) — a move that could ultimately scuttle Becker’s confirmation indefinitely.

Senate Democratic leaders needed the help of their entire 59-vote caucus, plus one Republican defector, to invoke cloture this Tuesday on Becker’s nomination, which has awaited a full Senate vote since the summer of 2009. But Nelson’s decision to oppose the White House’s top candidate for the job seriously threatens those plans, as it now appears Democrats will not have the votes they need to proceed as intended this week.

Nelson outlined his objections to Becker’s nomination in a statement issued late Monday, stressing he felt the former AFL-CIO lawyer would “take an aggressive personal agenda to the NLRB, and that he would pursue a personal agenda there, rather than that of the Administration.”

“This is of great concern, considering that the Board’s main responsibility is to resolve labor disputes with an even and impartial hand,” Nelson added. “In addition, the nominee’s statements fly in the face of Nebraska’s Right to Work laws, which have been credited in part with our excellent business climate that has attracted employers and many good jobs to Nebraska. Considering these matters, I will oppose the upcoming cloture motion and the nomination.”

An email sent from an Service Employees International Union (SEIU) lobbyist to Democratic members of the U.S. Senate shows that the SEIU had advance knowledge of when key votes on Craig Becker were to be held. Becker is one of Barack Obama’s nominees for the National Labor Relations Board.

The email was released by Jeri Thompson, co-host of the Fred Thompson Show. She will be discussing it in detail on her show, which begins at 12PM.

Thompson described the email as “marching orders to the Senate HELP Committee, telling them what their schedule was going to be.”

According to the email sent from Alison Reardon, legislative consultant for SEIU, “Your attendance is crucial to appointing Craig Becker to the National Labor Relations Board (NLRB). Please attend Thursday’s HELP Ex. Session to report out President Obama’s nomination of Craig Becker for Senate confirmation.”

The memo continues, “This is the highest priority for organized labor, and Majority Leader Reid will file Cloture on Friday 2/5, and has assured us that Senate will vote to end debate at 5 p.m. Monday 2/8.”

The email also asks for Senators to confirm their attendance at the executive session of the HELP Committee.